A Long Term Evolution (LTE) system supports a time division duplex (TDD) manner. That is, an uplink (UL) and a downlink (DL) use different timeslots of a same carrier. The uplink is used for uplink communication. That is, if user equipment (UE) has data to be sent to a base station, the user equipment sends the data by using the uplink. The downlink is used for downlink communication. That is, if a base station has data to be sent to a user equipment, the base station sends the data by using the downlink.
A round trip time (RTT) is an important indicator for measuring performance of a wireless communications system, and generally means a period from a time at which a transmit end sends data to a time at which the transmit end receives an acknowledgement from a receive end.
In a TDD system, data scheduling is generally performed in a hybrid automatic repeat request (HARQ) manner. For one HARQ process, after sending data, a transmit end does not send a next data packet until a preset maximum feedback latency elapses. Therefore, if an ACK can be received as soon as possible, a time interval at which data packets are sent in one HARQ process can be shortened, an RTT can be reduced, and data transmission efficiency can be improved.
Currently, there is still no method that can effectively reduce an RTT of a TDD communications system and improve data transmission efficiency.